Which of the following is an appropriate action for a rescuer when dealing with a choking casualty?

The most appropriate action for a rescuer dealing with a choking casualty is to perform back blows and abdominal thrusts. This method is specifically recommended by health authorities as it can help to dislodge the object that is blocking the airway.

Back blows involve the rescuer positioning themselves behind the victim and delivering firm blows to the back between the shoulder blades. This action can help create pressure that may dislodge the object. If back blows do not resolve the choking, abdominal thrusts—also known as the Heimlich maneuver—should be performed next. This technique consists of thrusting inward and upward just above the navel, which can force the object out of the airway due to the sudden increase in pressure.

Other actions mentioned, such as encouraging the victim to drink water, may worsen the situation by causing further obstruction. Starting chest compressions immediately is inappropriate because it is not part of the treatment for choking unless the victim becomes unresponsive and requires CPR. Leaving the victim alone could lead to a life-threatening situation, as they may continue to choke without assistance. Therefore, performing back blows and abdominal thrusts is the correct and effective response to help a choking individual.